help please iphone 4s?

Hi i recently brought a iphone 4s. i discovered it was jb, i no longer wanted the jailbreak on the device so i tried restoring the phone via itunes.

when i tried to restore it it come up that the device could not be restored and sent it into a boot logo loop, but when the boot logo is upi can still take screenshots and even use the triple touch command via home button and invert colours etc.

but if i hold the home button and power button and then the volume up button it comes up as it has been restored but will now get past the activation screen i have also pit it into recovery mode and tried to restore it it comes up i need to restore it and when i click okay the whole window shutsdown

please help me thanks in advace